Numpy Arange generating values of inconsistent decimal points

Question

Can someone explain me what's happening here?

Why is there more decimal points for 0.3 and 0.7 values. I just want 1 decimal point values.

threshold_range = np.arange(0.1,1,0.1)
threshold_range.tolist()

[Output]: [0.1, 0.2, 0.30000000000000004, 0.4, 0.5, 0.6, 0.7000000000000001, 0.8, 0.9]

Answer 1

Use np.round

Ex.

import numpy as np

threshold_range = np.arange(0.1,1,0.1)
print(threshold_range.tolist())
print(np.round(threshold_range, 2).tolist())

O/P:

[0.1, 0.2, 0.30000000000000004, 0.4, 0.5, 0.6, 0.7000000000000001, 0.8, 0.9]
[0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9]

Answer 2

Solution: You can simply use round function:

threshold_range = np.arange(0.1,1,0.1).round(1)
threshold_range.tolist() # [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9]

Reason of error: I think it has to do with floating point precision ;)